Vessels having corrosion resistant liners are well known for the purpose of reacting, processing and storing liquids having corrosive properties. Similar vessels are known for the purpose of preventing contamination of a vessel's contents by material leached from or adhering to corrosion prone materials.
Glass lined vessels are among the best of such corrosion and contamination resistant vessels. Glass linings are inert to most materials and may be manufactured to have very smooth surfaces to which contaminates either do not adhere or from which contaminates are easily removed.
Such glass lined vessels, unfortunately, do have disadvantages. In particular, glass lining of vessels, e.g. steel vessels, must be done with particular care to avoid stress cracks and to obtain desirable adherence. In addition, such glassing operations require high temperature furnaces. Glassing of vessels is thus relatively costly. Further, glass linings are brittle and thus may be subject to breach through both thermal and impact shock. This often occurs at the bottom nozzle of a vessel where there may be tight curves subject to thermal and expansion stress and where the vessel is subject to more physical contact than other parts of the vessel.
Once the lining is breached the only options to maintain corrosion resistance are temporary repairs to cover the area of the breach or reglassing which requires return of the vessel to the glassing factory.
Up to the time of the present invention, temporary repairs were not as good as desired for several reasons. A tight seal between undamaged glass lining and the repair must be obtained. This was not always effective or possible. There are a limited number of materials having sufficient corrosion and temperature resistance to make a good repair. Among these are certain fluoropolymers, e.g. polytetrafluoroethylene and certain exotic metals, e.g. tantalum. An example of such a repair is disclosed in bulletin SP-1A 9/91 of Spectrum Products, Inc. Unfortunately, the use of fluoropolymers, while being relatively inexpensive, does not permit repairs to be made that are as good as the original glass surface. Fluoropolymers, while having reasonably good temperature resistance, do not have nearly the temperature resistance of glass. Also, fluoropolymers do not have corrosion resistance as good as glass. In particular such polymers are subject to degradation by nascent halogens, e.g. chlorine, bromine and iodine.
It would therefore seem that the best option for such a "temporary" repair is an exotic metal such as tantalum. It is true that tantalum has a higher temperature resistance than fluoropolymers and have better resistance to halogens than fluoropolymers. Unfortunately, such metals are exceedingly costly and difficult to process especially in temporary repairs that must be discarded when the repair is removed for replacement of sealing gaskets or to permit reglassing.